1. Field of the Invention
The present invention relates to an equipment start-up control device, and in particular, to a device for stopping start-up of equipment when an improper operation is performed to start up the equipment, such as using a false key or unlawfully changing circuits.
2. Description of the Related Art
In an automobile or the like, locking devices which can be released by a genuine key are fitted to the doors or the like, and the engine can be started only by a genuine ignition key. In such a manner, it is attempted to prevent a vehicle from being stolen. Furthermore, in order to secure the theft prevention, it has been proposed to equip another theft prevention system and such a system is about to be put to practical use.
For example, Automobile Technique Application Publication No. 95603 (Japan Automobile Industry Association, Intellectual Property Section, published on Dec. 1, 1995) disclosed a vehicle theft preventing device which will prohibit start-up of an engine if a genuine ignition key is not used because it is interlocked with an ignition key.
In this vehicle theft preventing device, the ignition key is provided with a built-in transponder for transmitting a key code. An antenna installed in a key cylinder supplies power to the transponder by means radio waves, and the transponder transmits the key code stored. An immobilizer ECU is connected to the antenna in the key cylinder and determines whether or not a key code transmitted is correct. Further, the immobilizer ECU is connected with an engine ECU for controlling ignition of an engine and fuel injection and informs the engine ECU as to whether or not a correct key code has been obtained. If the immobilizer ECU cannot obtain the correct keycode, the engine ECU will prohibit the fuel injection into the engine and the ignition of the engine, thereby controlling the engine to stop. Thus, it is possible to prevent start-up of an engine and travelling of a vehicle when an attempt is made to start the engine without using a genuine key. The engine ECU starts the engine as usual in accordance with ignition which is brought about by operation of the ignition key, and stops the engine in response to a signal transmitted from the immobilizer ECU.
At the initial stage of start-up of the engine, a starter motor is rotated, whereby fluctuation of supply voltage is great. Therefore, communication between the immobilizer ECU and the engine ECU is performed after the engine speed becomes 500 rpm or more.
More specifically, when the engine speed becomes 500 rpm or more, the engine ECU generates a prescribed rolling code A by random number generation and sends it to the immobilizer ECU. If the genuine key has been recognized, the immobilizer ECU will generate a rolling code B by similar random number generation and will send it to the engine ECU in return. Thus, the engine ECU confirms that the genuine key was used. A key confirmation process is then completed, and normal operation of the engine is continued.
On the other hand, if a correct rolling code B is not sent back within a predetermined period of time, the engine ECU will stop the ignition and fuel injection. Thus, if the operation is not executed by using a genuine key, the engine will be stopped.
However, in this conventional example, the engine does not stop for approximately several seconds (for a period of time required to confirm that the rolling code has not been sent back) after the engine speed reaches 500 rpm. Thus, by repeating this operation without using a genuine key, the vehicle travels a certain distance.
There is also an idea that by providing a backup memory inside the engine ECU for storing the number of times the control for stopping the engine at the time of start-up is invoked, if there are several consecutive unusual start-up operations, start-up of the engine will be prevented.
However, there is a problem that if electric power is turned off by, for example, turning off the ignition switch before the engine is stopped by the aforementioned suspension control, the number of times control has been invoked will not be counted any further, unlike the case described above, and therefore travelling of the vehicle will be possible to some extent.
Further, there is another problem that if power supply to the backup memory is cut off, a value of the count up to the previous time will be cleared and therefore travelling of the vehicle will be possible to some extent.